• Phone +44-020-7040-4575
  • Fax + 44-020-7040-8580

Authors: T.Garel, G.Iori. H.Orland

Journal: Phys. Rev. B, Vol 53, No. 6, R2941-R2944 (1996)

Year: 1996

Status: Journal Articles

Abstract: A disorder-dependent Gaussian variational approach is applied to the d-dimensional ferromagnetic XY model in a random field. The randomness yields a nonextensive contribution to the variational free energy, implying a random mass term in correlation functions. The Imry-Ma low-temperature result, concerning the existence (d>4) or absence (d<4) of long-range order is obtained in a transparent way. The physical picture which emerges below d=4 is that of a marginally stable mixture of domains. We also calculate within this variational scheme, disorder-dependent correlation functions, as well as the probability distribution of the Imry-Ma domain size.

Link: http://dx.doi.org/10.1103/PhysRevB.53.R2941

Research Areas